Electric circuit controller



y 1945. A. P. CHARBONNEAU EI'AL 2,376,653

ELECTRIC G IRCUIT CONTROLLER Filed May 25, 1942 Patented May 22, 1945ELECTRIC cmcm'r con'raormn Allan P. Charbonneau, Frank J. Russell, andEdwin W. Seeger, Wauwatosa, Wls., assignorl to Cutler-Hammer, Inc.,Milwaukee, Wis a corporation oi Delaware Application May 25, 1942,Serial a... 444,304

Claims.

This invention relates to electric circuit controllers especiallyapplicable to the electrical equipment of airplanes, but not limited tosuch application.

Airplanes are commonly equipped with electric motors employed forvarious purposes and the motors are apt to become overloaded, whereforeit is desirable to equip the motors with overload protective meansailording automatic disconnection thereof prior to injury by overload.On the other hand, in some instances, particularly in the case offighting airplanes, it is important to make possible in emergenciescontinued operation of the controlled motor after occurrence of overloadconditions regardless of the danger of burnout.

An object of the present invention is to' provide-simple and reliablecontrol means aflording all aforementioned control and affording theaforementioned emergency control in a convenient and natural way.

Another object is to provide control means which upon termination of theaforementioned emergency operation leaves the controller in a conditionto function in the usual manner.

Another object is to-provide control means of the remote control typewhich will minimize danger of the motor circuit when closed, beingopened as the result of damage to the remote control element orconnection thereof.

Other objects and advantages of the invention will hereinafter appear.

The accompanying drawing illustrates diagrammatically one embodiment ofthe invention which will now be described, it being understood that theinvention is susceptible of embodiment in other forms without departingfrom the scope of the accompanying claims.

Referring to the drawing, the same shows a motor M to be connected to apower bus B and having a ground connection G. It is of course to beunderstood that the motor may be of any suitable type. Alsoit is to beunderstood that the motor circuit shown is merely a typical translatingcircuit and in lieu of a motor it might include some other translatingdevice.

For connecting the motor to bus B there is .provided an electromagneticswitch S having normally disengaged contacts S and an electromagneticwinding S to be energized to eflect engagement of said contacts. Inpractice the switch S may be of any one of a number of well known types.

A two-way switch having sets of contacts 2 and- 3 provides by engagementof its contacts 2 for connection 01' one terminal of the winding S tobus B, the other terminal of said winding having a ground connection GThus switch I provides for energizing the switch 8 to complete thecircult of motor M, but said switch preferably is of that well knowntype which returns to its intermediate or open position when released,thus tending to deenergize switch S. It will, of course, be understoodthat the two-way switch I might be replaced by two separate one-wayswitches each biased to open position.

For maintaining switch S energized following its energization by switchI there is provided a maintaining circuit including contacts 4 ofoverload switch 0L, a resistance R and the contacts S of switch S, theresistance R being of a value to prevent response or the motor to thecurrent supplied thereto through said resistance upon engagement ofcontacts 2 of switch I.

The overloa switch contacts 4 are normally engaged and when the switch Sresponds it completes circuit rtrom bus B, through its contacts Sresistance R and contacts 4 to the terminal of winding S connected toswitch I.

The overload switch 0L which in practice may be of any preferred type,either thermal or electromagnetic, is shown as having an operating coil5 in series with the motor M and upon responding said overload switchopens the maintaining circuit of switch 8 to deenergize the latter fordisconnection of the motor M, assuming switch I to be open. on the otherhand, the switch I may in emergencies be operated and held to engage itscontacts 2 thereby to insure continued energization of switch Sregardless of the action of the overload switch, and upon release ofswitch I the switch S is again placed under control of the overloadswitch.

In practice the switch S, .the overload switch 0L and the resistor R arepreferably built in unit form or at least assembled in a closerelationship for concentration of the maintaining connections of switchS and consequent minimization'of danger of these connections being hitand damaged in battle, As will appear, the connection between thewinding of switch S and the remote control switch I may be completelyshot away without affecting the switch S if at that instant it isenergized for completion oi. the motor circuit. Under such conditionsthe switch S would remain energized to keep the motor in action pendingresponse of the overload switch.

The control switch I through operation to engage its contacts 3 providesfor deenergization of switch S at will. Contacts 3 of switch I com-.plete a ground connection G" diverting current from the winding 8 ofswitch S to ground,

If it be desired to provide for indication of the position of thecontacts of switch 8 the controller enables such provision to be easilymade. Thus as shown a coil 8 for a suitable indicator may be connectedbetween the pivot or switch I and ground connection G whereby itscircuit will be completed by operation of switch I to energize switch Sand whereby it will be short circuited byoperation of switch I todeenergize switch S. Also the means described for maintaining thecircuit of switch S will maintain the circuit of coil '8.

It will be noted that when the switch S is deenergized by the overloadswitch the switch S will remain deenergized pending operation of thepilot switch to engageits contacts 2.

What we claim as new and desire to secure by Letters Patent is:

1. In combination, a translating circuit, a normally open switch in saidcircuit, said switch having a winding by energization 01' which it isclosed, a normally closed switch responsive to an overload condition ofsaid translating circuit, a circuit for said winding of the firstmentioned switch extending through said normally closed switch, andmeans to afford said winding control at will from a ,remote point andoptionally to mally open switch in said circuit, said switch having awinding by energization of which it is closed, a normally closed switchresponsive to an overload condition of said translating circuit, acircuit for said winding of the first mentioned switch extending throughsaid normally closed switch, and means to ailordsaid winding con.- trolat will from a remote point, said means to afford energization of saidwinding requiring operation in a given manner under all conditions andthereupon being releasable to render continued energization of saidwinding dependent upon said overload responsive switch or alternativelybeing restrainable to render continued energization of said windingindependent of said overload responsive switch.

3. In combination, a translating circuit, a normally open switch in saidcircuit, said switch having a winding by energization of which it isclosed, a switch responsive to an abnormal electrical condition in saidtranslating circuit, a pilot switch, energizing connections for saidswitch winding controlled by said pilot switch alone and a maintainingcircuit ior said switch winding comprising a connection between oneterminal of said switch winding and one side of said translating circuitat a point in the latter between the first recited switch and thetranslating device or said translating circuit, said connectionincluding a resistor and contacts of said switch responsive to anabnormal condition.

4. In combination, a translating device having a groundconnection, aswitch to establish a bus connection for said translating device, saidswitch having an electroresponsive winding to effect its closingoperation and said winding having a ground connection, a pilot switch toestablish a bus connection for said winding, a switch responsive to anoverload condition of said translating device anda maintaining circuitextending from said winding to the first recited switch for busconnection therethrough in common with the bus connection of saidtranslating device, said maintainin circuit including a resistor andcontacts of said overload responsive switch.

5. In combination, a translating device having a ground connection, aswitch to establish a bus connection for said translating device, saidswitch having an electroresponsive winding to efiect its closingoperation and said winding having for one terminal thereof a groundconnection, remote control means for said winding optionally toestablish a bus connection or a ground connection for the oppositeterminal of said winding, 9.

' switch responsive to an overload condition oi. said

